Hydraulic accumulator

ABSTRACT

The invention relates to a hydraulic accumulator, in particular a low-pressure accumulator, comprising an accumulator housing ( 2 ) and a separating element arranged therein, in particular in the form of an accumulator bladder ( 22 ) separating two media chambers ( 3, 5 ). The hydraulic accumulator is characterized in that the accumulator housing ( 2 ) is formed of at least two shells ( 8, 10 ) welded together at their opposing end regions ( 24 ).

The invention relates to a hydraulic accumulator, in particular a low-pressure accumulator, comprising an accumulator housing and a separating element arranged therein, in particular in the form of an accumulator bladder separating two media chambers from each other.

Hydraulic accumulators are frequently used in systems, in which flowable media such as hydraulic oil or other pressure fluids or lubricants and/or fuels are used as operating media. To this end, hydraulic accumulators can be used, for instance, for energy storage purposes, to provide a fluid reserve, the emergency operation of loads, the absorption of pressure shocks and the like. Given the wide range of tasks for which hydraulic accumulators are used, hydraulic accumulators are produced in relatively large quantities. The amount of production costs and the resulting costs to the user of the hydraulic accumulator therefore are of great economic importance.

With regard to this problem, the invention addresses the problem of providing a hydraulic accumulator, especially in the form of a low-pressure accumulator, which can be manufactured at particular low cost.

According to the characterizing part of claim 1, one essential feature of the invention is that the accumulator housing is in the form of at least two shells, which are welded to one another at their mutually facing end regions. The formation of the accumulator housing in the form of a closed welded structure, i.e. without a detachable port for opening the housing with associated sealing means, allows the accumulator to be manufactured particularly efficiently and inexpensively as a so-called “disposable accumulator”. For the embodiment as a non-openable disposable accumulator, in which the accumulator bladder installed before welding cannot be replaced in case of damage, there is no requirement for a bore of sufficient size for the assembly or exchange of the bladder in the accumulator housing, i.e. high structural strength of the container can be achieved with particularly little effort.

In particularly advantageous exemplary embodiments, the accumulator housing has two half-shells having a circular cylindrical sidewall and a spherical bottom. Particularly advantageously, the half-shells can be provided in the form of identical parts.

The production is particularly efficient and cost saving if deep-drawn shells of a metallic material are provided for the accumulator housing.

In particularly advantageous exemplary embodiments, a central bore is formed in the bottom of a half-shell through which an accumulator bladder, which at its opening is held in tight contact to the edge of the bore, can be filled with working gas.

Particularly advantageously, a fluid port can be provided in the center of the bottom of a further half-shell. This fluid port can be designed such that strainer holes are formed in the bottom of the half-shell. In particular for relatively low pilot pressures, a protective strainer can be formed at the fluid port in a particularly cost-saving manner. In addition, a shut-off valve can be arranged at the fluid port.

The invention also provides a method for manufacturing a hydraulic accumulator according to claims 1 to 8, said method comprising the method steps specified in claim 9.

The invention is explained in detail below, using an exemplary embodiment depicted in the drawing.

In the drawings:

FIG. 1 shows an oblique perspective view of an exemplary embodiment of the hydraulic accumulator according to the invention reduced compared to a practical embodiment roughly by a factor of 3 and

FIG. 2 shows a slightly simplified schematic, cutaway view of FIG. 1.

The exemplary embodiment of the hydraulic accumulator according to the invention in the form of a bladder accumulator depicted in the drawing comprises an accumulator housing 2 in the form of a circular cylinder that is closed at both ends by end parts 4 and 6, each similarly spherically curved. As can be seen most clearly from the sectional view of FIG. 2, the housing 2 consists of two identical parts designed as half-shells 8 and 10. These half-shells 8, 10 are made of a metallic material by deep-drawing, so that the end parts 4, 6 each form the shell bottom of the respective one-piece half-shell 8 and 10, respectively. In the central area of the bottom of every half-shell 8, 10, i.e. coaxially to the cylinder axis, a media passage is formed. For this purpose, a bore 12 for a connecting part 14 is provided in the upper—in the drawing—end part 6. This leads to the gas side 5 of the accumulator, which is formed by the interior of an accumulator bladder 22, which separates the gas side 5 from the surrounding fluid side 3. In the manner known per se for bladder accumulators, the connecting part 14 passes through the bore 12 in the end part 6 and has a flange 18 at its inner end. This is engaged with a rim flange 20 located on the filling opening 16 of the accumulator bladder 22 made of elastomeric material. By means of a nut 24 on the threaded shank of the connecting part 14, the filling opening 16 of the bladder 22 can be tightly braced against the edge of the bore 12 of the end part 6. As the accumulator housing 2 can no longer be opened at their respective end rims 24 after the half-shells 8, 10 have been welded, the accumulator bladder 22 mounted before welding can be no longer be dismantled after the housing 2 is closed, because the bore 12, which is solely used to form the filling port and is dimensioned correspondingly small, does not permit the installation or removal of the accumulator bladder 22. The design of the housing 2 without a bore of a size sufficient for the installation or removal of the bladder 22 is highly advantageous for the structural strength of the accumulator housing 2.

At the end part 4, which forms the lower—in the drawing—shell bottom, a fluid port 26 is provided as a media passageway. In the hydraulic accumulator according to the invention, which is designed for pilot pressures of the accumulator bladder 22 in the low pressure area, for instance for a rated pressure of 16 bar, the fluid port 26 may have a perforation, which forms a strainer hole 28, in the central part of the end part 4 that is coaxial to the cylinder axis. A connecting element 32 is attached to the end part 4 by means of a weld 30. In the present exemplary embodiment, the connecting element 32 has a fluid valve in the form of a stopcock 36 actuated by means of a rotary knob 34.

The weld at the end rims 24 is advantageously configured such that the circumferential weld bead 38 extends on the outside of the housing 2 and the inner wall of the housing remains smooth across the separation line, so that no harmful chafing occurs if the bladder 22 comes in contact with moving parts. Unlike the exemplary embodiment shown, in which the housing 2 is completely constructed from two half-shells 8, 10, an additional shell part or a plurality of shell parts in the form of pipe sections may be welded between the half-shells 8, 10. Also, in the low-pressure area considered, a plastic material suitable particularly for thermoforming may be provided for the accumulator housing 2. 

1. A hydraulic accumulator, in particular a low-pressure accumulator, comprising an accumulator housing (2) and a separating element arranged therein, in particular in the form of an accumulator bladder (22) separating two media chambers (3, 5) from each other, characterized in that the accumulator housing (2) is formed of at least two shells (8, 10) which are welded to each another at their mutually facing end regions (24).
 2. The hydraulic accumulator according to claim 1, characterized in that the accumulator housing has two half-shells (8, 10) with a circular cylindrical sidewall and a spherical bottom (4, 6).
 3. The hydraulic accumulator according to claim 1, characterized in that the half-shells (10, 8) are provided in the form of identical parts.
 4. The hydraulic accumulator according to claim 1, characterized in that deep-drawn shells (8, 10) of metallic material are provided.
 5. The hydraulic accumulator according to claim 1, characterized in that in one half-shell (10) a central bore (12) is formed, through which an accumulator bladder (22), the opening (16) of which is held in tight contact with the edge of the bore (12), can be filled with working gas.
 6. The hydraulic accumulator according to claim 1, characterized in that a fluid port (26) is provided in the center of the bottom (4) of a further half-shell (8).
 7. The hydraulic accumulator according to claim 1, characterized in that at the fluid port (26) strainer holes (28) are formed in the bottom (4) of the half-shell (8).
 8. The hydraulic accumulator according to claim 1, characterized in that a shut-off valve (36) is disposed at the fluid port (26).
 9. A method for manufacturing a hydraulic accumulator according to claim 1 comprising the sequential stages: Manufacture of at least two shells (8, 10); Forming a media passage (12, 28) at the bottom (4 and/or 6) of the shells (8, 10); Attaching the opening (16) of an accumulator bladder (22) to the media passage (12) of a shell (10) and Manufacture of a closed accumulator housing (2) containing an accumulator bladder (22), by welding the shells (8, 10) at their rims (24).
 10. The method according to claim 9, characterized in that shells (8, 10) of a metallic material are formed by deep drawing. 